Okay so while I don't play VGC, I just have some general things to offer on movesets which may be more of use to you. n_n
For Politoed you don't need Surf AND HPump on something without a choiced item because it generally wastes a moveslot. While I can see why you used Surf, perhaps you could replace HPump with HP Grass to be able to hit ground/water types which you can otherwise really do nothing to, and you already have the boosted Surf to be able to hit everything else just to a lesser extent than you would with HPump.
On Rotom-W go for Leftovers > Sitrus since you have longer recovery and all. Also while you have Toxic, you have nothing really to help stall out the walls other than Scizor which probably isn't the best thing for stalling. Adding to that, Rotom-W has no recovery other than leftovers so possibly consider going with Thunder Wave instead to help you out against more offensive Pokemon because your team is pretty much mostly offensive rather than defensive Pokemon and thus offensive are more likely to present you issues if that makes sense!
On Toxicroak you could benefit from Substitute since Surf will help you out with the lost HP and you already have Drain Punch to help recover, so you don't necessarily need the second fighting attack.
Aaand on Starmie you're better off giving it Surf > Scald because Starmie tends to go for power rather than the "chance" of hax.
Either way that's about all without knowing the exact ins/outs of what is actually common in VGC etc.